Friday, October 31, 2014

Car Collision Physics

I was involved in a car accident. My car was
thrown 83 feet. The guy who hit me was driving a 2002 Thunderbird,
weighing 3,775 pounds. My car was a 2006 Toyota Matrix, weighing 2,679
pounds. Is there any way that I can calculate how fast his car was going
at the point of impact? I was turning left, and the guy smashed into my
passenger side as I crossed his lane. I would say the angle at which he
hit me was about 110 degrees, since I wasn’t quite at 90 degrees to him
yet. I was just starting to turn, so I was going no more than 5 mph. I
ended up 83 feet away. There were no tire tracks at the point of impact,
so my car must have gone airborne! This seems like a physics problem,
and I have contacted some physics students, but they are students and
are not interested. I think it should be possible to calculate it, but I
don’t know physics. Please help! My car was totaled. The other guy
claims he was going 35 mph, but given how far my car went, that just
doesn’t make sense.

The thing that I'm interested in more than anything else is what else is needed to accurately model this event. This person didn't describe if his car skidded all the way till it stopped, or simply roll away. He also didn't say how far his car was "airborne".

This is why an investigator will need to actually look at the scene itself to get a more complete set of parameters. People who are involved in this usually do not realize what are all the necessary information that are needed to reconstruct the event.

3 comments:

Hi Zapper, I used to crash analysis for a commercial insurance company for a short time, just as an fyi. The first thing that comes to mind is the surface and it's condition in which your vehicle was pushed across. Less resistance. Also the differential of weight to force less the unknown of resistance factors can be significant. Without pictures of the vehicles to analyze, surface area etc, a basic mathematical approach without an accounting of the other variables will simply not be accurate. However it is enough to possibly dispute the claim of 35mph. your welcome to pm me for further information. Sorry to hear about the collision, glad your not injured.

Oh, I was going to follow up as I realized with no marks the car was lifted thus hit on the lower part of the car having least amount of energy loss through material absorption. The inertia of force from the simple Newtonian equation dictates more than enough energy to propel the car well over 85' also allowing for surface resistance, contact surface area of tires, hitting curbs etc. Doesn't sound like much impact energy was lost in body panels and such or even the road it seems. But I'm taking a realistic approach to include observable variables and not purely mathematical. So, glad it wasn't you!